In the time domain analysis of vehicle ride comfort, the veracity of the input excitation signals is directly related to the simulation result. The random road model was constructed by Matlab/Simulink based on the study of the relation of stochastic road space and time frequency power spectral density (PSD) and PSD and root-mean-square (RMS). The stochastic excitation signals were produced, and the vertical displacement of the B and C level uneven road was built by simulation with different vehicle velocities. By PSD and RMS analysis of vertical displacement of simulation result and national standards, the correctness of model was confirmed. That can offer reliable excitation signals for control research of vehicle. It proves that the idea and methods of modeling is unique and practical.